American Mineralogist, Volume 91, pages 1945–1954, 2006 New mineral names* ANDREW J. LOCOCK,1 T. SCOTT ERCIT,2,‡ JOHAN KJELLMAN3, AND PAULA C. PIILONEN2,† 1Department of Earth and Atmospheric Sciences, University of Alberta, Edmonton T6G 2E3, Canada 2Research Division, Canadian Museum of Nature, P.O. Box 3443, Stn. D, Ottawa, ON K1P 6P4, Canada 3Department of Earth Sciences, Uppsala University, SE-752 36 Uppsala, Sweden – ALLANITE-(LA)* and the strongest lines [d in Å (I, hkl)]: 7.93 (15,101), 3.506 – – (20,211), 2.901 (100,113), 2.806 (40,020), 2.692 (60,013), 2.611 P. Orlandi, M. Pasero (2006) Allanite-(La) from Buca della Vena – – – – mine, Apuan Alps, Italy, an epidote-group mineral. Can. (50,311), 2.283 (15,114), 2.174 (25,401), 1.632 (20,233), 1.432 – 3 Mineral., 44, 523–531. (15,613). Dmeas = 3.93(1) g/cm by ß otation in heavy liquids, Dcalc = 3.94 g/cm3 for Z = 2. Allanite-(La) is found in close association with calcite and The root name allanite honors the Scottish mineralogist barite in barite veins that cut a dolomitic metamorphosed lime- Thomas Allan (1777–1833) who Þ rst studied the mineral, and stone in the Castello zone of the Buca della Vena mine, near the name allanite-(La) reß ects its relationship with allanite-(Ce), Stazzema, Apuan Alps, Tuscany, Italy. It occurs as prismatic the Levinson modiÞ er indicating the dominant REE. The authors crystals, elongated along [010], up to 2–3 mm in length. The emphasize that specimens with compositions corresponding to mineral is well crystallized and not metamict, with principal allanite-(La) have been known in the literature for some time, and – forms {001}, {100}, {101}, {101}, {210}, and {011}. It is that although this name has been used previously on an informal brittle, H = 6, transparent to translucent, black with brownish basis, the formal description and naming of allanite-(La) Þ lls a reß ections and a brown streak, vitreous, with imperfect cleavage gap in the nomenclature of approved epidote-group minerals. parallel to {001} and conchoidal fracture. Allanite-(La) is biaxial, The mineral corresponds to IMA mineral no. 2003-065. Type material is deposited in the Centro Interdipartimentale Museo di nx = 1.755(5), ny = 1.760(5), nz = 1.765(5), 2V = 90(2)°, orienta- tion Y = b, has very high dispersion and is strongly pleochroic, Storia Naturale e del Territorio of the University of Pisa, under with Y greenish to olive green and Z greenish brown. The aver- catalog no. 10478. A.J.L. age of eight electron microprobe analyses gave SiO2 32.45, TiO2 0.10, ThO2 0.31, Al2O3 17.77, Y2O3 0.035, La2O3 8.51, Ce2O3 CHISTYAKOVAITE-(Y)* 6.12, Pr2O3 3.16, Nd2O3 3.53, MgO 0.32, CaO 13.01, FeOtot N.V. Chukanov, G.A. Sidorenko, I.S. Naumova, A.E. Zadov, 13.67 (FeO 8.72, Fe2O3 5.50 on the basis of stoichiometry), H2O V.I. Kuz’min (2006) Chistyakovaite, a new mineral Al(UO2)2 (calc) 1.63, sum 100.62 wt% (for FeOtot), 101.17 wt% (for FeO (AsO4)2(F,OH)·6.5H2O. Dokl. Earth Sci., 407, 290–293 (in + Fe2O3), corresponding (on the basis of 25 negative charges and English); Dokl. Akad. Nauk, 406, 816–819 (in Russian). 8 cations) to: Ca1.000[(La0.288Ce0.206Nd0.116Pr0.106Y0.001)Σ0.717Ca0.279 3+ 2+ 3+ Th0.006]Σ1.002(Al0.899Fe 0.101)Σ1.000Al1.000(Fe 0.669Fe 0.279Mg0.044Ti0.007)Σ0.999 The new species chistyakovaite occurs in samples collected [(Si0.978Al0.022)Σ1.000O4](Si2O7)O(OH), which can be simpliÞ ed as 2+ 3+ in the 1950s from the supergene zone of the Bota-Burum deposit, Ca(REE,Ca)Al2(Fe ,Fe )(SiO4)(Si2O7)O(OH) with La dominant in the A2 site. south of Alakol’ Lake, southwestern Balkhash area, Zhambyl Single-crystal X-ray structure study (R1 = 0.0328) conÞ rmed (Dzhambul) Region, Kazakhstan. This hydrothermal U deposit that allanite-(La) is a member of the epidote group: monoclinic, consists of carbonatized felsite porphyries and tuffaceous brec- cias of Devonian age that have undergone primary hydrothermal space group P21/m, a = 8.914(4), b = 5.726(1), c = 10.132(6)Å, β = 114.87(5)°, V = 469.1(3) Å3. Powder diffraction data were alteration and subsequent supergene alteration. In particular, su- collected with a GandolÞ camera (57.3 mm diameter, CuKα pergene alteration of hydrothermal arsenopyrite and pitchblende radiation) and yielded reÞ ned unit-cell parameters a = 8.875(6), is responsible for liberating the U and As responsible for the b = 5.735(2), c = 10.088(7) Å, β = 114.88(4)°, V = 469.1(3) Å3, new species and many other uranyl-bearing arsenates found at the deposit. The mineral is associated with arsenopyrite, pyrite, galena, scorodite, arseniosiderite, mansÞ eldite, metazeunerite, * Before publication, minerals marked with an asterisk were approved by the Commission on New Minerals and Mineral trögerite, and sodium uranospinite. It forms imperfect, {100} Names, International Mineralogical Association. ß attened, yellow crystals to 2 mm across, which are sometimes † E-mail: [email protected] intergrown. Brittle; Mohs’ hardness 2.5; Dmeas 3.62(2), Dcalc 3.585 ‡ English translations of articles are available upon request from g/cm3; perfect {100} and imperfect {001} cleavage; stepped T.S.E. ([email protected]). fracture. Bright green luminescence in UV light (365 nm). Opti- 0003-004X/06/1112–1945$05.00/DOI: 10.2138/am.2006.477 1945 1946 NEW MINERAL NAMES – cally biaxial (–), colorless, with α = 1.557(2), β = 1.580(1), γ = be triclinic, space group P1, a = 12.138(3), b = 12.196(3), c = 1.580(1), 2V = –10(5)°, X = a, Z ≈ b, no dispersion. Dissolves 15.944(4) Å, α = 78.537(5), β = 84.715(4), γ = 60.470(4)°, V = in HCl at room temperature with no liberated gas. The infrared 2013(1) Å3. The complex crystal structure can be considered to spectrum (KBr pellet, 400 to 4000 cm–1 range) records vibration be layered parallel to (001) and to consist of three main slabs and/or ß exing bands for H2O, OH, PO4, UO2, AsO4, and AlO6; of cation-centered polyhedra, two with the idealized trigonal a large shoulder at 3130 cm–1 implies the existence of some plane-symmetry and one with monoclinic symmetry. One of the strong hydrogen bonding. Heating in Ar to 850 °C gives a total pseudotrigonal slabs is the basis of a hypothetical homologous weight loss of 12.2%. This, combined with electron microprobe series of cyclically twinned sulfosalt structures. The internal analysis (20 kV, 10 nA, 50 μm, except for F at 15 kV, 70 nA, symmetries of the slabs lead to a twin law with (100) as the 50–60 μm beam) gave: Al2O3 4.99, UO3 58.34, As2O5 21.40, P2O5 twin plane, and make possible the existence of several potential 1.23, F 1.1, H2O 12.2, O=F –0.46, total 98.80 wt%, yielding the OD (order-disorder) polytypes. Metal–metal bonds (Tl–Tl and empirical formula (per 2 AsO4 + PO4), Al0.96(UO2)2.00[(AsO4)1.83 Tl–Cu) and metal–semimetal (Tl–As) bonds are notable features (PO4)0.17][F0.57(OH)0.31]·6.50H2O, or ideally Al(UO2)2(AsO4)2(F, in the structure and help to explain the low hardness and metallic OH)·6.50H2O. Gladstone-Dale compatibility is good. Fracturing character of the mineral. Powder diffraction data were collected and mosaic structure precluded single-crystal study, but powder with a Debye-Scherrer camera (114.6 mm diameter, FeKα ra- X-ray diffraction study gave space groups P2/m, P2 or Pm, a = diation) and yielded reÞ ned unit-cell parameters a = 12.152(7), 19.99(1), b = 9.79(1), c = 19.62(2) Å, β = 110.7(2) °, Z = 8. The b = 12.203(7), c = 15.965(5) Å, α = 78.25(6), β = 84.55(6), γ mineral, which would seem to be the arsenate-ß uorine analog = 60.65(7)°, V = 2020(2) Å3, and the strongest lines [d in Å (I, – of threadgoldite, has also possibly been found at the Menzen- hkl)]: 15.631 (100,001), 5.237 (40,121), 3.944 (40,321), 3.531 – – schwand deposit in the Schwarzwald, Germany. Chistyakovite is (80,300), 3.468 (40,233), 3.263 (50,031), 3.143 (90,214), 2.978 – 3 named for N.I. Chistyakova, a senior assistant at the All-Russia (60,324), 2.911 (70,422), 2.520 (60,223). Dcalc = 5.41 g/cm for Research Institute of Mineral Resources (VIMS). Type samples the ideal formula and Z = 6. are in the E.V. Kopchenova collection of the Mineralogical Mu- The mineral is found in association with numerous other As seum at VIMS, (no. 350/59), and in the Fersman Mineralogical sulfosalts, including hutchinsonite, hatchite, edenharterite, trech- Museum, Moscow (no. 3286/1). mannite, tennantite, abundant realgar, and rathite, in cavities in a Discussion. No mention is made of whether peak shape Triassic dolomitic rock at Lengenbach, Binntal, Canton Valais, corrections were applied to the FKα microprobe data. Errors Switzerland. The name honors Walter Gabriel (b. 1943), of Basel, as large as 20% rel. can be incurred without such corrections Switzerland, a well-known mineral photographer and expert on (Solberg, T.N., 1982, Microbeam Analysis, 17, 148–150), an Lengenbach minerals. The mineral corresponds to IMA mineral important concern when the (F,OH) site contains only 0.57 F no.